This invention relates to container filling devices. It has particular applicability to a low-cost, easy-to-use filling device for dispensing high-viscosity liquid dispersions of iron oxide pigment, although the usefulness of the invention is not limited to that application.
Iron oxide pigments are widely used in industry and commercially to provide yellow, red, and black coloring and blends including these three primary colors. A common example of their use is in coloring concrete and mortar. In these applications, it is frequently useful to have relatively small quantities (a pint, a quart, or up to five gallons) of pigment in colors to match a larger job. Dispensing such small quantities of the pigment into containers for use on a job site is now extremely difficult for a number of reasons.
Synthetic iron oxide powders are commonly dispersed in water to make the fine powder easier to work with. These aqueous dispersions may include small amounts of additives such as surfactants. The aqueous dispersions are dense, having a specific gravity on the order of 2.5. Therefore, handling even relatively small volumes of the dispersions can be awkward, particularly if containers must be lifted in confined areas.
They are abrasive. Therefore, the equipment used in dispensing them must be particularly durable.
They are very viscous and thixotropic; their viscosity varies with temperature, pressure, agitation, color, and other conditions. Obtaining uniform flow is therefore difficult, and timed filling processes cannot generally be used. The variances in viscosity also complicate the problem of avoiding dripping and splashing of the materials. When exposed to air, they become sticky, then harden; they therefore clog orifices, valves and other surfaces they come in contact with.
The liquid pigments are very concentrated. Less than five percent pigment by weight of the cement is required for a concrete masonry mix including one part by weight of standard Portland cement and six parts sand. One quart of liquid pigment is typically used to make one hundred gallons of paint. The pigments are so concentrated that spills are difficult to clean, and handling equipment requires lengthy clean-up. Even a spill of a drop or two may require substantial effort to clean up. Therefore, dispensing equipment which drips after shut-off or which splashes can cause major disruptions. Moreover, switching from one color to another requires cleaning the handling equipment thoroughly to prevent mixing of colors.
Presently known dispensing equipment is expensive, difficult to use, and does not meet the foregoing requirements.